JP2528710B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, more specifically, a photoconductive layer provided with a charge generation material and a specific charge transport material on a conductive support. The present invention relates to an electrophotographic photosensitive member.

[Prior Art] In recent years, widely used as electrophotographic photosensitive materials,
Examples of the inorganic photoconductive substance include α-selenium, cadmium sulfide, and α-silicon, and examples of the organic photoconductive substance include poly-N-vinylcarbazole and polyvinylanthracene. , Each of which has considerable problems such as price, performance or toxicity.

For the purpose of compensating for these drawbacks and increasing the sensitivity, a method has been actively proposed in which the two functions of the photoconductive substance, that is, the charge generation and the transport of the generated charge are performed by separate organic compounds, respectively. Have been. In these methods, a high-sensitivity electrophotographic photoreceptor can be obtained by stacking and combining a substance having a high charge carrier generation efficiency (charge generating substance) and a substance having a high charge transporting ability (charge transporting substance). The possibility is expected. However, whether or not the characteristics required for the electrophotographic photoreceptor, that is, having high surface potential and charge holding ability, high photosensitivity, and characteristics such as having almost no residual potential are simply satisfied. These combinations alone cannot be predicted.

Conventionally, N-alkylcarbazole-3-carbaldehydediphenylhydrazone has been used as a charge transport material (Patent Document 1)
54-150128), N-alkylphenothiazine-3-carbaldehyde diphenylhydrazone (JP-A-57-58157).
No.), p-dialkylaminobenzaldehyde diphenylhydrazone (Japanese Patent Publication No. 55-42380) and the like have been proposed.

[Problems to be Solved by the Invention]

However, the electrophotographic photosensitive member using the hydrazone as a charge transport material is not sufficient in photosensitivity, and when repeatedly used repeatedly in accordance with the electrophotographic process, the ability to restore the original charging characteristics is deteriorated. However, there are practical problems such as shortening the life of the photoconductor such as increase in residual potential. Further, in recent years, with the speeding up and downsizing of electrophotographic copying machines, printers, etc., fast responsiveness to the photoconductor has been demanded, but these requirements are not yet satisfied. Is.

[Means for solving the problem]

In view of such circumstances, the inventors of the present invention have conducted diligent research on the charge transport material, and as a result, a specific 4 '-(N, N-diphenylamino) biphenyl-4-carbaldehydehydrazone derivative was excellent in solving the above problems. The present invention has been completed by finding out that it is a charge transport material.

That is, the present invention provides an electrophotographic photosensitive member comprising a conductive support and a photosensitive layer containing a charge generating substance and a charge transporting substance, which is represented by the following general formula (I) as a charge transporting substance. The present invention provides an electrophotographic photoreceptor containing a-(N, N-diphenylamino) biphenyl-4-carbaldehydehydrazone derivative.

(In the formula, R ₁ and R ₂ represent the same or different lower alkyl groups, benzyl groups or phenyl groups, or both may be bonded to form a heterocycle with the adjacent nitrogen atom) 4 '-(N, N represented by the formula (I)
Typical examples of the -diphenylamino) biphenyl-4-carbaldehydehydrazone derivative include the following.

These compounds are produced, for example, by the method represented by the following reaction formula.

(In the formula, R ₁ and R ₂ are the same as above.) First, Tamura et al. [“Nippon Kagaku Magazine”, Vol. 92, No. 11, 1021]
~ 1023 (1971)], 4-biphenylcarbonitrile (III) is reacted with iodine and periodic acid to obtain 4'-iodobiphenyl-4-carbonitrile (IV). Then, F. Ullmann (Chem. Ber., 36 , 2382 (190
3)], (IV) and diphenylamine are condensed in sulfolane (tetrahydrothiophene-1,1-oxide) in the presence of a copper catalyst and a base (K ₂ CO ₃ ) to give 4 ′-(N, N-diphenylamino) biphenyl-4
-Carbonitrile (V) is obtained. (V) was reacted with 0.5 equivalent or slightly excess of Vitride [sodium bis (2-methoxy) aluminum hydride], and then hydrolyzed with 30% sulfuric acid to obtain 4 '-(N, N-diphenyl). Amino) biphenyl-4-carbaldehyde (V
I get. Further, in (VI), a hydrazine (VII) or a salt thereof, in the presence of a condensing agent (eg, tertiary amines such as pyridine and triethylamine, inorganic acids, organic acids such as acetic acid),
The reaction is carried out in a solvent (alcohols such as methanol, ethanol, etc., tetrahydrofuran, acetic acid) at a reflux temperature of the solvent or a temperature lower than the reflux temperature to obtain a 4 ′-(N, N-diphenylamino) biphenyl-4-carbaldehydehydrazone derivative (I ) Get.

Next, the electrophotographic photoreceptor of the present invention using (I) as the charge transport substance will be described with reference to basic examples.

FIG. 1 shows an example of the electrophotographic photosensitive member of the present invention, in which a charge generating layer 3 mainly composed of a charge generating substance 2 and a compound (I) of the present invention are uniformly formed on a conductive support 1. And a charge transport layer 4 contained in the photosensitive layer 5.

That is, in the photoreceptor shown in FIG. 1, the light transmitted through the charge transport layer reaches the charge generating substance dispersed in the charge generating layer to generate the charge, and the charge transport layer injects the charge. It receives and carries out the transportation.

In order to produce the photoreceptor of FIG. 1, first, a charge generating substance is vacuum-deposited on a conductive support, and a dispersion liquid obtained by mixing and dispersing fine particles of the charge generating substance with a binder as necessary is prepared. The charge generating layer is formed by means such as coating and drying, coating a solution of a charge generating substance dissolved in a suitable solvent, and drying. Then, a solution containing the compound of formula (I) and a binder is applied onto the charge generation layer and dried to form a charge transport layer. If necessary, a conventionally known substance having a charge transporting ability may be used in combination. The application is carried out using a conventional means such as a doctor blade or a wire bar.

The charge generation layer has a thickness of 5 μm or less, preferably 2 μm or less, and the charge transport layer has a thickness of 3 to 50 μm, preferably 5 μm or less.
20μ. Further, the compounding ratio of the compound of the formula (I) in the charge transport layer is 10 to 90% by weight (hereinafter simply referred to as “%”),
It is preferably 30 to 70%.

As the conductive support, a metal plate such as aluminum, a metal foil or a metal tube, a plastic film on which a metal such as aluminum is vapor-deposited, or paper subjected to a conductive treatment is used. As the binder, a polyester resin, a polyvinyl chloride resin, an acrylic resin, a methacrylic resin, a polystyrene resin, a polycarbonate resin, or the like is used. Among them, the polyester resin and the polycarbonate resin are preferable.

Examples of the charge generating substance include amorphous selenium,
Examples of the inorganic materials such as arsenic cerium, cadmium sulfide, and amorphous silicon, and organic materials include bisazo pigments; trisazo pigments; phthalocyanine pigments; indigo pigments; perylene pigments; squarylium pigments; polycyclic quinone pigments; Examples thereof include pyrylium-based dyes, but the dyes are not limited to these and may be any one that absorbs light to generate an electric charge.

2 and 3 show another example of the photographic photosensitive member of the present invention. That is, FIG. 2 shows that a dispersion liquid obtained by mixing and dispersing fine particles of a charge generating substance together with a binder on a conductive support 1 is coated with a coating liquid in which a compound of formula (I) is uniformly dissolved, The photosensitive layer 5 formed by drying is provided. In this case, the thickness of the photosensitive layer is 5 to 50 μm, preferably 10 to 25 μm. In addition, FIG. 3 shows a structure in which a charge transport layer containing a compound of formula (I) is coated on the conductive support 1 in the reverse of the structure of FIG. 1, and a charge generation layer is coated thereon. is there. Further, if necessary, an undercoat layer may be provided between the conductive support 1 and the photosensitive layer 5. As the undercoat layer,
Polyamide, polyurethane, polyvinyl alcohol, casein, nitrocellulose, gelatin, etc. are used. The thickness of the undercoat layer is preferably 0.1 to 1 μm.

〔The invention's effect〕

The photoconductor of the present invention obtained as described above has excellent characteristics such as extremely high sensitivity, high flexibility, no change in characteristics due to charging exposure, and high durability.

After charging the photoreceptor of the present invention using a commercially available electronic copying machine,
When the toner image obtained by exposing through the original image to develop an electrostatic latent image was developed using a developer and the obtained toner image was transferred and fixed on plain paper, a clear copy image faithful to the original image was obtained.

〔Example〕

Next, the present invention will be described in more detail with reference to Synthesis Examples and Examples, but the present invention is not limited thereto.

Synthesis Example 1 (1) Synthesis of 4'-iodobiphenyl-4-carbonitrile [compound (IV)]: 4-cyanobiphenyl 17.9 g (0.1 mol), metaperiodic acid dihydrate 5 g (0.022 mol) , Iodine 13g (0.051mol), acetic acid 49ml, water 10ml and concentrated sulfuric acid 1.5ml 70
Stirred at ℃ for 1 day.

The reaction mixture obtained was washed with aqueous sodium sulfite solution,
It was extracted twice with 1 l of benzene. The obtained benzene layer was washed with saturated brine, dried over magnesium sulfate, and concentrated to give 24.5 g of crystals. This crystal is ethanol-
Recrystallized from ethyl acetate (5: 1) ml, melting point 179-181 ℃
Crystal of 4'-iodobiphenyl-4-carbonitrile of
18.5 g (yield 60.6%) was obtained.

_{IR (CHCl 3); 3010,2230 (} CN), 1610,1480,1385cm -1 1 H-NMR (400MHz, CDCl 3); δ 7.32 (d, J = 8Hz, 2H),
7.64 (d, J = 8Hz, 2H), 7.72 (d, J = 8Hz, 2H), 7.81 (d, J
= 8Hz, 2H) MS; 305,177,151,127,104,101,77,75,51 (2) Synthesis of 4 '-(N, N-diphenylamino) biphenyl-4-carbonitrile [compound (V)]: 4'-iodobiphenyl-4 -Carbonitrile (IV)
11 g (36.1 mmol), diphenylamine 5 g (29.5 mmol), copper powder 2.3 g (36.2 mmol), potassium carbonate 5 g
(36.1 mmol) and a small amount of iodine were reacted in 100 ml of tetrahydrothiophene-1,1-dioxide at 180 ° C. for 5 hours. After confirming the disappearance of diphenylamine by thin-layer chromatography, the mixture was filtered while hot to remove inorganic substances, the filtrate was poured into water, and the mixture was extracted 3 times with 200 ml of benzene. The obtained benzene layer was washed with brine, dried over magnesium sulfate, concentrated, and subjected to silica gel chromatography (solvent: benzene) to obtain 6.5 g of an oily substance. Crystallization of this oily substance using 200 ml of ethanol gave 4.17 g of crystals of 4 '-(N, N-diphenylamino) biphenyl-4-carbonitrile having a melting point of 141-142 ° C.
(Yield 40.8%) was obtained.

_{IR (CHCl 3); 3010,2225 (} CN), 1590,1490,1330cm -1 1 H-NMR (400MHz, CDCl 3); δ 7.05-7.10 (m, 2H), 7.
10-7.16 (m, 6H), 7.25-7.32 (m, 4H), 7.46 (d, J = 8H
z, 2H), 7.64-7.70 (m, 4H) MS; 346,341,268,243,167,77 (3) Synthesis of 4 '-(N, N-diphenylamino) biphenyl-4-carbaldehyde [compound (VI)]: 4'- (N, N-diphenylamino) biphenyl-4-
4.2 g (12.12 mmol) of carbonitrile (V) was dissolved in 50 ml of tetrahydrofuran and cooled in an ice bath, and 1.8 g (6.23 mmol) of a 70% toluene solution of vitrid was added to this solution.
It was added dropwise to -3 ° C over 10 minutes. The reaction was monitored by thin-layer chromatography, and vitrid was added little by little so that the vitrid was slightly excessive to complete the reaction. Thereafter, the mixture was stirred at 5 ° C or lower for 4 hours, and 50 ml of 30% sulfuric acid was added.
The mixture was stirred overnight at room temperature, neutralized with 40% aqueous sodium hydroxide solution, extracted with 200 ml of benzene three times, and the benzene layer was washed with brine. The benzene layer was dried over magnesium sulfate, concentrated, and then subjected to silica gel chromatography (solvent: benzene) to obtain 3.36 g of crystals. This was recrystallized from 100 ml of ethyl acetate-ethanol (1: 2) to obtain 2.4 g of crystals (yield 56.7%) having a melting point of 119 ° C.

_{IR (CHCl 3); 3020,1700 (} CHO), 1590,1520,1490cm -1 1 H-NMR (400MHz, CDCl 3); δ 7.05-7.10 (m, 2H), 7.
10-7.16 (m, 6H), 7.22-7.35 (m, 4H), 7.50 (d, J = 8H
z, 2H), 7.75 (d, J = 8Hz, 2H), 7.95 (d, J = 8Hz, 2H), 10.
05 (s, 1H) MS; 349.320,243,167,141,77 (4) Synthesis of 4 '-(N, N-diphenylamino) biphenyl-4-carbaldehydemethylphenylhydrazone [Compound (I-1)]: 4'- (N, N-diphenylamino) biphenyl-4-
500 mg (1.43 mmol) carbaldehyde (VI) and 200 mg (1.64 mmol) methylphenylhydrazine were refluxed in 20 ml ethanol with a few drops of acetic acid for 3 hours. The obtained reaction mixture was concentrated and subjected to silica gel column chromatography (solvent: benzene) to give 620 mg of crystals. Recrystallization with 40 ml of ethyl acetate-ethanol (1: 1) gave 580 mg (yield 89.4%) of crystals of 4 '-(N, N-diphenylamino) biphenyl-4-carbaldehydemethylphenylhydrazone having a melting point of 187 ° C. Was obtained.

^{_{IR (CHCl 3); 3000,1590,1490,1380cm -1}} 1 H-NMR (400MHz, CDCl 3); δ 3.45 (s, 3H), 6.90-7.
00 (m, 1H), 7.00-7.05 (m, 2H), 7.10-7.20 (m, 5H),
7.20-7.40 (m, 9H), 7.50-7.60 (m, 5H), 7.70-7.80
(M, 2H) MS; 453,346,320,266,227,168,152,141,106,91,77,65 Synthesis Example 2 In the same manner as in Synthesis Example 1, the following compound was obtained.

Example 1 (i) 0.2 g of chlorcian blue was added to a polycarbonate resin (“Upilon E-200 manufactured by Mitsubishi Gas Chemical Co., Inc.”
0 ") was mixed with 4 g of a dichloroethane solution containing 5%, 20 ml of dichloroethane was added, and then 1 μ was used using a vibration mill.
To make a dispersion of the charge carrier generating pigment by pulverizing below, on a polyester film vapor-deposited of aluminum,
Apply using a wire bar and dry at 45 ° C to about 1μ
The charge carrier generating layer was formed to a thickness of. On the other hand, the compound (I-
0.2 g of each of 1) to (I-4) was dissolved in 2 g of a dichloroethane solution containing 10% of the above polycarbonate resin to prepare a charge transport layer forming liquid, which was formed on the above charge carrier generating layer using a doctor blade. Then, it was applied so that the film thickness would be about 20 μm when dried, and dried at 80 ° C. for 2 hours to prepare a photoreceptor.

(Ii) For this photoconductor, an electrostatic copying paper test device "SP-
Electrostatic characteristics were measured by static method using "428 type" (manufactured by Kawaguchi Denki Seisakusho). That is, the photoreceptor was charged by performing a corona discharge of −6 KV for 5 seconds to measure the surface potential V ₀ (unit −volt), which was kept in the dark for 5 seconds, and then an illuminance of 5 with a tungsten lamp.
The amount of exposure required to attenuate the surface potential to 1/2 and 1/6 by irradiating the light of looks E _1/2 lux · second) and E _1/6 (lux · second), and the light of illumination 5 lux residual surface potential after irradiation for 10 seconds V _R (- V) was measured. The results are shown in Table 1 below.

A photosensitive member similar to (i) above was prepared using a compound of the following formula disclosed in JP-A-54-150128 as a comparative compound, and tested in the same manner as (ii). This result is also the first
Shown in the table.

Example 2 Titanium phthalocyanine was vacuum-deposited on a thin aluminum film deposited on a polyester film at 10 ⁻⁶ Torr to a thickness of about 0.8 μm to form a charge generation layer. Ten
% Dichloroethane solution containing polycarbonate resin
A charge-transporting layer-forming solution prepared by dissolving 0.2 g of each of the compounds (I-1) to (I-4) in 2 g was formed on the charge-generating layer using a doctor blade to give a dry film thickness of 22 μm. And then dried at 80 ° C. for 3 hours to prepare a photoconductor. Table 2 shows the results of measurement performed on this photoconductor in the same manner as in Example 1.

[Brief description of drawings]

1 to 3 are cross-sectional explanatory views showing an example of the electrophotographic photosensitive member of the present invention. 1 ... Conductive support, 2 ... Charge generating substance, 3 ... Charge generating layer, 4 ... Charge transporting layer, 5 ... Photosensitive layer.

Claims (1)

(57) [Claims] 1. An electrophotographic photosensitive member comprising a conductive support and a photosensitive layer containing a charge generating substance and a charge transporting substance provided on the conductive support.
The following general formula (I) is used as the charge transport material. (Wherein R ₁ and R ₂ represent the same or different lower alkyl group, benzyl group or phenyl group, or they may be bonded to each other to form a heterocycle with an adjacent nitrogen atom) An electrophotographic photosensitive member comprising a 4 '-(N, N-diphenylamino) biphenyl-4-carbaldehydehydrazone derivative.